When a vehicle collides, an airbag apparatus expands toward a vehicle compartment by gas supplied from an inflator, whereby constraining an occupant.
Priority is claimed on Japanese Patent Application No. 2011-009689, filed Jan. 20, 2011, the content of which is incorporated herein by reference.
In addition, when an airbag (corresponding to “airbag body” of the present application) expands and when an occupant is constrained by the airbag after the airbag expands, it is necessary to appropriately set the internal pressure of the airbag.
Specifically, when the airbag expands, it is necessary to instantly set the internal pressure of the airbag in a high-pressure state in order to quickly inflate the airbag.
Furthermore, when an occupant is constrained by the airbag, it is necessary to suppress the excessive increase of the internal pressure of the airbag in order to absorb the collision energy.
Therefore, a vent hole to release gas when an occupant is constrained is normally provided in an airbag apparatus.
When the airbag expands, the vent hole is closed, and therefore, the internal pressure of the airbag is instantly in a high-pressure state.
In addition, when an occupant is constrained by the airbag, the vent hole is opened, and therefore, the excessive increase of the internal pressure of the airbag when the occupant is constrained is suppressed (see Patent Document 1, for example).
The airbag apparatus disclosed in Patent Document 1 includes an inflator opening, a vent hole provided on a side portion of the inflator opening, and a vent hole cover to close the vent hole.
The vent hole cover is joined to the airbag at a sewing portion, and therefore, the vent hole is closed.
Furthermore, when the airbag expands, the vent hole cover prevents gas supplied from an inflator from leaking through the vent hole.
If the airbag inflates corresponding to the increase of the internal pressure of the airbag during the expansion of the airbag, the sewing portion is ruptured. Subsequently, the vent hole cover comes off and the vent hole is opened.
In addition, after the airbag expands, the gas in the airbag is released through the vent hole, whereby the excessive increase of the internal pressure of the airbag is suppressed when an occupant is constrained by the airbag.